Photoluminescence of n-type Cdsub(x)Hgsub(1-x)Te epitaxial layers

Photoluminescence (PL) is investigated of n-type Cdsub(x)Hgsub(1-x)Te epitaxial layers in the constant composition regions and in the region with the composition gradient present. Optical excitation was applied at the layer side and recombination radiation was observed both at the layer side (reflection geometry) and at the substrate side. The analysis of radiation spectra has shown that a short wave radiation band is connected with the interzonal recombination, while long-wave band - with the conductivitone-acceptor transitions. The estimation of ionization energy of acceptors, participating in radiative transitions, from the energy distance between radiation bands gives Esub(A)=30 MeV. According to the estimates, screening of minority localized states (excitons and donors) by free carriers in Cdsub(0.3)Hgsub(0.7)Te takes place already at the free carrier concentration n approximately 1015 cm-3. Therefore, there are no radiation lines related to minority states, such as (A0, x) and donors, in the PL spectrum